An in-depth study of the preparation, purification, and determination of the physical and chemical properties of a variety of rare earth porphyrin materials will be undertaken. Both synthetic and mechanistic studies will be employed in determining the optimum methods for preparing and handling such materials for employment as molecular biological probes. Their spectroscopic, emission, and magnetic properties once established will allow their use as rather unique probes to study various aspects of hemeprotein phenomena, the photodynamic action of porphyrins in certain neoplasias, and the role of antenna vs, active site chlorophyll in photosynthesis. Synthetic, analytical, kinetic, and spectroscopic methods will all be utilized in the investigation.